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In an investigation for the Daily Mail, security consultant Adam Laurie has demonstrated how a new UK biometric passport can be cloned without even being removed from its delivery envelope.

The Mail exploit draws on previous work by Laurie and others, and puts together vulnerabilities in the chip technology, and in the chip security and logistics systems used by the Identity & Passport Service.

The data in the chip is essentially a digital version of what is printed inside the passport itself. The printed data can be read if the passport is presented and opened, and the chip's security system attempts to duplicate this process. The chip data can be read wirelessly, but it is encrypted, with the key printed inside the passport. So in theory, although the chip can be read without the passport (or indeed the delivery envelope) being opened, the data is meaningless without the key.

But the key in this first generation of biometric passport is relatively easy to identify/crack. It is not random, but consists of passport number, the passport holder's date of birth and the passport expiry date. The Mail found it relatively easy to identify the holder's date of birth, while the expiry date is 10 years from the issue date, which for a newly-delivered passport would clearly fall within a few days. The passport number consists of a number of predictable elements, including an identifier for the issuing office, so effectively a significant part of the key can be reconstructed from the envelope and its address label.

Laurie established the theory of this last year, but the Mail report puts it into practice. With the cooperation of the applicant, the newly-delivered passport envelope was rerouted, and a working key was identified within four hours. Once this has been done, a fraudster would have all of the information needed to copy the chip, and therefore would be some considerable distance closer to being able to produce an identical copy of the entire passport.

The Mail notes that no proof of identity was required when the passport was delivered, but the vulnerabilities exposed mean that the problem goes far beyond the occasional passport being cloned after its delivery has been intercepted. Because it's feasible to steal the data without detection, it's perfectly possible that insiders could intercept large numbers of the millions of new passports delivered every year.

If, that is, there is a point to doing so. At the moment the value of the data is limited because the chip can only be copied, not changed, so it can only be used as an aid in the forgery of a copy of an existing passport (although some possible exploits based on this are described here). Passport forgers would still have to produce a viable copy of the passport book itself, and the resulting document could only be used by someone of similar appearance to the original owner.

That, however, is the current state of play, not necessarily the end of the story. One of the primary reasons the chip is being introduced is because historically, passport forgers have been able to forge successive generations of book passports, with each new iteration of security eventually being matched by the bad guys.

Once biometric passports are commonplace the forgers will need to be able to deal with the chips in them, and if they want to stay in business they'll need to be able to change the data, not just copy it.

Without access to the digital signature used by the passport issuing authority to protect the integrity of the data, this can't be done. The forgers could therefore attempt to crack the signature for the passport variety of their choice, but simply gaining access to the key via corrupt officials or espionage could turn out to be a quicker route. With this in mind, it's worth noting that ICAO, which devised the system, anticipates that keys will be compromised, and puts forward steps that should be taken to protect the system when this happens.

If, however, this turns out to happen a lot (how many of the world's passport issuing authorities would you trust?), then chip security will quite possible turn out to be just one more increment in the passport forgery arms race. ®